Granted IPFW is a fantastic firewall - Might I recommend a more syntax friendly firewall PF.
I am not trying to deter you from your IPFW, over the years I noticed a increasing amount of people switching (depends on needs), so you might want to take a gander.
Most will use IPFW w/ DummyNET for QoS -- The PF alternative, ALTq is good but not as polished as dummynet. Personally I'd still go with PF